The invention relates to a tap for discharging liquid from a container, with a tap bushing that can be set into an opening in the container, with a seal, which tap bushing is provided with a passage opening for the liquid, and with a piston guided so as to move axially within the tap bushing, which piston has an entry opening and an exit opening for the liquid, whereby the piston closes off the passage opening of the tap bushing in a locked position when it is moved into the tap bushing, and whereby the entry opening of the piston is in connection with the passage opening of the tap bushing in an extended position of the piston, in which it is moved out of the tap bushing, and a flow path through the piston can be released and blocked off by means of rotational activation.
Such a tap is known from DE 198 25 929 A1. The tap is designed for a rotational activation of the piston. When the piston is moved out of the tap bushing, it can be rotated from the locked position in which it closes off the passage opening of the bunghole bushing, into a release position in which the entry opening of the piston is in connection with the passage opening of the tap bushing, and vice versa. In the release position, liquid exits from the exit opening of the piston, which functions as the discharge opening of the tap.
The tap of DE 198 25 929 A1 is of a mature design that has been well proven in practice. The tap is particularly characterized by a high level of operational reliability and a high level of operating ease. Cost-effective production and assembly of the tap are guaranteed because it is composed of only two parts.
The known tap is primarily used to discharge liquids that contain carbon dioxide and have been packaged under pressure, particularly beverages, from barrels, small barrels (party barrels), or cans. What is particularly involved is party barrels for beer.
It is felt to be a disadvantage of the known tap that it drips when discharging liquids that contain carbon dioxide and have been packaged under pressure. When the tap is first opened, the interior of the tap bushing and the cavity of the piston fill with liquid. When the tap is closed, a residue of liquid remains in the tap bushing and the piston, downstream from the passage opening of the tap bushing. The carbon dioxide contained in the residue of liquid relaxes and allows more liquid to exit from the tap. This is the known dripping effect.
It is understood that dripping is undesirable, since it can result in stains, and hygiene problems can occur.
Another disadvantage of the known tap is that when the piston is activated by rotation, the discharge direction of the liquid being discharged changes. It should be noted that the change is not great, but it can make it more difficult to fill small and slender vessels.
It is the task of the invention to create a tap of the type stated initially, which is free of any dripping and has a fixed discharge direction, while changing the design as little as possible, keeping the outside dimensions practically the same and, very important, offering the same type of operation. The new tap is supposed to be able to replace the tap of DE 198 25 929 A1, with the user practically not noticing the difference, only that the tap does not drip and that the discharge direction is not influenced by the rotational activation.
This task is accomplished, with such a tap, in that a locking bushing that is guided to rotate on the piston is seated in the piston, which locking bushing has a passage opening and can be rotated from a locked position in which it closes off the exit opening of the piston, into a release position in which the exit opening of the piston is in connection with the passage opening, and vice versa.
According to the invention, the exit opening of the piston is closed or released, respectively, by rotational activation of a locking bushing seated in it. In the locked position of the locking bushing, liquid that is located in the tap cannot exit, i.e. the tap cannot drip.
The exit opening of the piston functions as the discharge opening of the tap. Since it is not the piston but rather the locking bushing that is rotated within it, the discharge direction of the tap remains unchanged during the rotational activation.
In the tap according to the invention, the piston can be moved solely in an axial direction. In other words, no rotational adjustment of the piston is provided. This makes it possible to simplify the structure of the piston.
In the tap according to the invention, the rotational adjustment of the locking bushing is uncoupled from the axial adjustment of the piston. The user can therefore pull the piston out of the tap bushing and rotate the locking bushing in the piston, independently of one another. Incorrect operation cannot occur in this connection, since liquid exits from the tap only if the piston has been pulled sufficiently far out of the tap bushing, and if the locking bushing has been rotated sufficiently far in the piston.
The tap according to the invention is made of three parts and is therefore somewhat more complicated in its production and assembly than the two-part tap according to DE 198 25 929 A1. The accompanying somewhat higher production and assembly costs are more than made up by the advantage that it does not drip and that the discharge direction is fixed.
Compared with the tap according to DE 198 25 929 A1, there are no increased requirements with regard to originality protection for the tap according to the invention.
In a preferred exemplary embodiment, the entry opening and the exit opening of the piston lie on its bottom in a common radial plane. This structure is made possible by the purely axial adjustment of the piston in the tap bushing. In this way, a simplified construction of the piston and a discharge direction precisely downward are achieved.
In a preferred embodiment, the piston has a contact stop to limit its extended position out of the tap bushing.
In a preferred embodiment, the locking bushing is limited by a contact stop that limits its rotational movement in the piston, towards both sides.
In a preferred embodiment, a shield is provided on the outer face of the locking bushing, and a handle stirrup is divided from this shield.
In a preferred embodiment, the handle stirrup is provided with an elastic covering. In this way, the ease of operation of the tap and its value appeal are significantly increased for the user.
In a preferred embodiment, the covering of the handle stirrup is textured on its surface, in such a way as to improve its feel, particularly it is provided with ribs or ridges. This increases the ease of operation of the tap.
In a preferred embodiment, the covering is molded onto the handle stirrup using two-component injection-molding technology. This is preferred for cost reasons.
In a preferred embodiment, the handle stirrup is connected to the tap bushing at at least one predetermined breaking point. The connection consists of the elastic material of the covering. This also serves to increase the ease of operation.